We are moving, so my original 845 manual is already hidden in a box
somewhere, for several weeks, sorry.
As far as I remember, the online manuals are quite complete.
Search for "845" on the fluke sites, and you will find two manuals, one
for the 845AB, the other for the 845AR.
Please check, if the scanned AR version is more complete.
The circuitry is practically identical to the DVM part of the 335D
calibrator, it's very simple, so you won't miss anything with those 3
manuals.
Frank